Influence of fasting on circulating levels of α-tocopherol and β-carotene. Effect of short-term supplementation

Abstract

We investigated the influence of fasting on the levels of α-tocopherol in plasma, erythrocytes and platelets, and on plasma β-carotene. Six apparently healthy adults were subjected to 17-h feed-fasting experiments at various days before, during and after supplementation with α-tocopherol (455 mg/day, 41 days) and β-carotene (25 mg/day, 24 days). Adipose tissue α-tocopherol and β-carotene were measured at regular intervals. Supplementation increased α-tocopherol and β-carotene in all compartments, except for β-carotene in adipose tissue. Discontinuation caused a rapid return to baseline, except for adipose tissue α-tocopherol and plasma β-carotene. Fasting caused linear increases of free fatty acids, consistent (but small) increases of plasma α-tocopherol and inconsistent increases of plasma β-carotene. There were no fasting-related changes in other compartments. We conclude that fasting is unable to increase α-tocopherol and β-carotene in circulating lipoproteins and cells to a considerable extent, both at baseline levels and after short-term supplementation. Maintenance of high levels may necessitate regular high oral intakes.